A method for producing pouches comprising the steps of providing a continuous web, folding the web to provide confronting side surfaces joined along a bottom edge and forming a vertical seal between the confronting side surfaces, thereby providing a series of adjacent pockets having opposite side walls, with each pocket having an unsealed opening along a top edge, and filling the pockets through the opening with material and then sealing the opening to provide sealed pouches is known from WO 2007/089838 A2.
In the known method, the continuous web is guided through a vertical sealer in which the vertical seals are formed after the continuous web has been folded. Those vertical seals are spaced from one another to provide a pocket which is defined by the bottom edge as the bottom of the pocket and a leading edge which is defined by a vertical seal, and a trailing edge which is defined by the neighboring vertical seal. The vertical seal is provided such that neighboring pockets can be separated without impeding the closure of the pocket by the vertical seal. By separating the pockets, individual pouches are formed.
In the method known from WO 2007/089838 A2, the continuous web is transferred to a cutting section in which the continuous web is cut to isolate individual pouches having an unsealed opening along the top edge. Those pouches are transferred by a vacuum belt transport means against which the separated pouches are sucked and transferred to a filler wheel. The filler wheel has gripping elements which are adapted to grip the leading and trailing edges of each pouch, respectively, between jaws and are movable relative to each other to open the unsealed opening. As the distance between the leading and the trailing edges of one single pouch is reduced, the distance between the confronting side surfaces in increased. Accordingly, spouts of a spout wheel can be introduced into the pouches for filling the same with material. The spout wheel and the filler wheel are rotatably driven. The rotational axis of the filler wheel is essentially co-axial to the rotational axis of the spout wheel. However, the rotational axes are slightly inclined relative to each other. At a circumferential section in which the distance between the spout wheel and the filler wheel is at its minimum, a respective spout is received within the open mouth of the pouches and then continuously retracted from the pouch as the filler wheel and the spout wheel are continuously rotated, starting from this position.
After the pouches have been filled, the gripping means are actuated such that the distance between the leading and the trailing edges of the each spout are increased, thereby bringing the confronting side surfaces closer together and closing the unsealed opening. In the course of the circular path along the outer circumference of the filler wheel, the pouches are finally sealed by a sealing section arranged at the outer circumference of the filler wheel and provided with heated sealing surfaces abutting against the folded web material for sealing the opening.
The method known from WO 2007/089838 A2 and the apparatus for carrying out said method is disadvantageous in that it requires a fusible film material for making the web. The fusible material is e.g. a plastic foil forming the web. However, fusible film materials are not suitable for packing brewable or extractible commodities like e.g. tea, coffee or the like, as foil material as such is not permeable for water.
U.S. Pat. No. 2,787,548 A describes a pouch in the form of a tea bag, the confronting side surfaces thereof being formed by a filter paper. This filter paper is coated with a thermoplastic coating, such that the entire confronting side surfaces defining a pocket for receiving the brewable or extractable commodity is coated. The web material disclosed in this prior art is fusible and, hence, suitable for being processed in the method known from WO 2007/089838 A2. However, coating of the entire confronting side surfaces of the pouch is disadvantageous as it may impede the taste of a fluid made by extracting or brewing the commodity contained in the pouch. Further, the thermoplastic coating on the filter material not only affect the taste, but also prevents or at least prolongs composting of the pouches after use.
It is an object of the present invention to provide a pouch not having the aforementioned drawbacks and a method for producing the same.